Excellent feedback from everybody, and great ideas. I've explored a lot of different door types, both hinged and more unique. I really like the way pantograph doors move up and out of the way on buses and bus-style class A coaches. But, as with gas shocks, they eat up space and have lots of moving parts. And I love using heavy duty drawer slides, but worry that tieing them into the door will limit loading options (unless I build in some sort of hinge for the drawer/door front). My generator enclosure box is mounted on heavy-duty slides so all sides can be easily accessed when needed.
Because I'm over budget on both time and money on this project, it's tempting to just take the easiest path, even though it might not be the best. So, with all your comments and ideas in mind, I spent some time walking around the rig late yesterday, paying special attention to how each door would be used, as well as it's interaction with other aspects of the camper. Even though it might take a little longer, your comments have inspired me to deal with each doors' unique needs.
For example, the two largest doors allow access to the waste water tanks (driver's side) and the generator/toy tank (passenger side). Neither have any storage capacity, they're just there in case I have to service or remove the components.
Waste water compartment (closest to the cab in the image below): The pull-handles for the empty valves are inside the waste compartment, but I can easily install a small, pre-fabricated (big plus) access hatch for each, or even a remote actuator system (also available in either manual, using cables, or electric). So that compartment is a candidate for a hingeless, completely removable door, as Shachagra suggested.
Genset/toy tank (closest to the front in the image below): This compartment opening has the same dimensions as the waste water door. Since the generator control panel is inside the camper, it only needs to be accessed for service/maintenance. This compartment also contains access the toy tank ( extends back under the interior steps and doubles as the generator fuel tank). I had intended to have the fill port and to the pump-out nozzle inside to avoid tampering. However, it might make more sense to install the fuel fill-port on the outside (again, using a locking, pre-fabricated hatch/cap set available through several manufacturers). I would need to install an access door within the larger compartment panel for the pump-out nozzle. The hose itself may be the biggest problem, since I don't believe I have room for a auto-retract spool. If I do, then it might be a candidate for a completely removable door. I would probably use two or more bolts, in addition to the locking Trimark handles I purchased for all of these doors.
The propane bottle compartment (behind the side personnel door in the image above) may be perfect for a drawer assembly. Due to the solar/battery capacity, and the fact that the primary heating is electric radiant, I won't be using a ton of propane. And, like the generator, it's a fixed component that has a set foot print. I would just need to make sure the hoses are long enough to articulate with the drawer slide.
I'm leaning towards side mount hinges for the rest of the doors, which are almost square, and provide access to storage compartments. The two rear compartments are complete "pass through", so there's a door on each side.
And speaking of Shachagra's reference to a real-life Tetris game, we burned up a day replacing the rollers for the big slide out room. This build is a game of tight tolerances, so, after adding 1/4" aluminum wear strips for the original rollers, the room would potentially rub on the ceiling during extension/retraction. In addition, the original five rollers, which are standard issue in the RV industry, are, of course, cheese.
I ordered a box of 20 and we buggered several of them already. So, I came up with this:
5 actual sealed bearing assemblies (only 4 are visible in the shot above), recessed and mounted on stainless axles. It gave me the clearance needed, as well as much greater piece of mind.
While this build began in the world of composites, it seems to be finishing in the world of aluminum. There are aluminum shavings in every nook and cranny of the shop, but at least it doesn't itch!